Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes

Tabelin, Carlito Baltazar; Seno, Kensuke; Jeon, Sanghee; Ito, Mayumi; Hiroyoshi, Naoki

doi:10.1016/j.chemosphere.2018.04.088

Cited by 74 publications

(31 citation statements)

References 54 publications

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“…They concluded that Fe‐catecholate complexes can suppress pyrite oxidation by the formation of an iron oxyhydroxide coating or by their electron donating effects. Park et al studied the effect of aluminum catecholate complexes on pyrite and arsenopyrite oxidations. The results show that the surfaces of pyrite and arsenopyrite form an Al‐oxyhydroxide (γ‐AlO(OH)) coating to inhibit their oxidation.…”

Section: Pyrite Oxidationmentioning

confidence: 99%

Pyrite oxidation mechanism in aqueous medium

Feng

Tian

Huang

et al. 2019

J Chinese Chemical Soc

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The mineral pyrite is considered the most common form of the sulfide minerals. Its oxidation is a very important process in nature, which involves in the redox recycling of iron. However, because of the growing need for the industrial production, sulfide oxidation produces more and more acid mine (or rock) drainage. This acid drainage has become a heavy economic and environmental problem. This review describes the oxidation mechanism of pyrite in an aqueous medium, including general oxidation and microbial oxidation, where sulfate, ferrous ion, S0, polysulfides, iron[III], and some intermediate species are formed. Also included is recent evidence on the electrochemical oxidation determined using the electrochemical method, X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and other techniques. In addition, the factors that influence the oxidation and dissolution rate, and the descriptive approaches for different species are discussed.

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Section: Pyrite Oxidationmentioning

confidence: 99%

Pyrite oxidation mechanism in aqueous medium

Feng

Tian

Huang

et al. 2019

J Chinese Chemical Soc

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“…An arsenopyrite electrode, a platinum (Pt) electrode, and an Ag/AgCl electrode filled with saturated KCl were used as working, counter, and reference electrodes, respectively. Preparation of the arsenopyrite electrode was described in our previous work [5].…”

Section: Electrochemical Studiesmentioning

confidence: 99%

“…For example, prolonged exposure even to minute amounts of As increases the risks of developing several types of cancers [1]. To mitigate this problem, carrier-microencapsulation (CME), a process that forms a protective coating on the surface of sulfide minerals, was developed by the authors [2][3][4][5]. In CME, a redoxsensitive organic compound (e.g., catechol, 1,2dihydroxybenzene, C6H4(OH)2) is used to transform relatively insoluble metal(loid) ions, such as Ti 4+ , Si 4+ , and Al 3+ , into soluble complexes.…”

Section: Introductionmentioning

confidence: 99%

Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

Tabelin

Inano

et al. 2019

MATEC Web Conf.

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Arsenopyrite is the most common arsenic-bearing sulfide mineral in nature. It is readily oxidized and releases toxic arsenic (As) into the environment when exposed to atmospheric conditions via anthropogenic activities like mining, mineral processing, extractive metallurgy, and underground space developments. Carrier-microencapsulation (CME) is a technique that uses metal(loid)-organic complexes to selectively form protective coatings on the surfaces of sulfide minerals. In this study, CME using Al-catecholate complexes (i.e., Al-based CME) was investigated to suppress the oxidation of arsenopyrite. Aluminum(III) and catechol form three complex species depending on the pH and among them, [Al(cat)]+ was the most effective in suppressing arsenopyrite oxidation. Its suppressive effect was improved as [Al(cat)]+ concentration increased due most likely to the formation of a more extensive surface protective coating at higher concentrations. Surface characterization of leaching residues using SEM-EDX and XPS indicates that CME-treated arsenopyrite was covered with bayerite (γ-Al(OH)3). The results of electrochemical studies showed that the surface protective coatings suppressed both anodic and cathodic half-cell reactions of arsenopyrite oxidation.

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“…Under atmospheric conditions, sulfide minerals in the tailings are readily oxidized when exposed to oxygen (O2) and water, resulting in the formation of acid mine drainage (AMD), one of the most undesirable consequences of mining activities due to its serious negative impacts to the surrounding environment [1]. Among the sulfide minerals, arsenopyrite is particularly notorious because its dissolution not only generates acidity but also releases arsenic (As), a toxic element known to increase the risks of developing numerous diseases like hyperpigmentation, keratosis, anemia, neuropathy, and several types of cancers even at minute amounts [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…The metalcatecholate complex decomposes on the surface of sulfide minerals that dissolve electrochemically. Finally, metal ions freed from the complex precipitate and form a protective coating on the mineral surface limiting the access of oxidants (i.e., O2 and ferric ion) [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Carrier-microencapsulation using Al-catecholate complex to suppress arsenopyrite oxidation: Evaluation of the coating stability under simulated weathering conditions

Seno

Tabelin

et al. 2019

MATEC Web Conf.

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Arsenopyrite (FeAsS) is the most common primary arsenic-sulfide mineral in nature, and its oxidation causes the release of toxic arsenic (As). To mitigate these problems, carrier-microencapsulation (CME), a technique that passivates sulfide minerals by covering their surfaces with a protective coating, has been developed. In the previous study of authors on CME, Al-catecholate complex significantly suppressed arsenopyrite oxidation via electron donating effects of the complex and the formation of an Aloxyhydroxide coating. For the application of this technique to real tailings, however, further study should be carried out to elucidate long-term effectiveness of the coating to suppress arsenopyrite oxidation. This study investigates the stability of the coating formed on arsenopyrite by Al-based CME using weathering tests. The Al-oxyhydroxide coating suppressed arsenopyrite oxidation until about 50 days of the experiment, but after this, the amounts of oxidation products like dissolved S and As increased due to the gradual dissolution of the coating with time as a result of the low pH of leachate. This suggests that co-disposal of Al-based CME-treated arsenopyrite with minerals that have appropriate neutralization potentials, so that the pH is maintained at around 5 to 8 where Al-oxyhydroxide is stable.

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Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes

Cited by 74 publications

References 54 publications

Pyrite oxidation mechanism in aqueous medium

Pyrite oxidation mechanism in aqueous medium

Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation

Carrier-microencapsulation using Al-catecholate complex to suppress arsenopyrite oxidation: Evaluation of the coating stability under simulated weathering conditions

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